The analog-to-digital converters (ADCs) used in pulse-height spectroscopic analyzers displaying amplitude probability distributions of electric signals require low differential non-linearity (DNL) and low conversion time. Commercially available ADCs cannot be directly used for spectroscopic applications, since DNL associated with them can be as high as .+-.1 least significant bit (LSB). This is unacceptable for spectroscopic applications, which require a DNL of .+-.1/100 LSB. Many techniques have been developed to achieve this requirement. These techniques rise sharply in complexity as a direct result of higher resolution and utilization of full ADC dynamic range.